[cairo-spline] Add a cache of eight points to cairo_spline_t

Most of the splines need not more than eight points.  This avoids
calling malloc() for those cases, and eight-points take only 64 bytes.

1 files changed, 23 insertions, 5 deletions

diff --git a/src/cairo-spline.c b/src/cairo-spline.c
index 726dc8606..d8dd477eb 100644
--- a/src/cairo-spline.c
+++ b/src/cairo-spline.c
@@ -90,22 +90,40 @@ _cairo_spline_init (cairo_spline_t *spline,
 void
 _cairo_spline_fini (cairo_spline_t *spline)
 {
-    spline->num_points = 0;
-    spline->points_size = 0;
-    free (spline->points);
+    if (spline->points != spline->points_embedded)
+	free (spline->points);
+
     spline->points = NULL;
+    spline->points_size = 0;
+    spline->num_points = 0;
 }
 
+/* make room for at least one more trap */
 static cairo_status_t
 _cairo_spline_grow (cairo_spline_t *spline)
 {
     cairo_point_t *new_points;
     int old_size = spline->points_size;
-    int new_size = old_size ? 2 * old_size : 32;
+    int embedded_size = sizeof (spline->points_embedded) / sizeof (spline->points_embedded[0]);
+    int new_size = 2 * MAX (old_size, 16);
+
+    /* we have a local buffer at spline->points_embedded.  try to fulfill the request
+     * from there. */
+    if (old_size < embedded_size) {
+	spline->points = spline->points_embedded;
+	spline->points_size = embedded_size;
+	return CAIRO_STATUS_SUCCESS;
+    }
 
     assert (spline->num_points <= spline->points_size);
 
-    new_points = realloc (spline->points, new_size * sizeof (cairo_point_t));
+    if (spline->points == spline->points_embedded) {
+	new_points = malloc (new_size * sizeof (cairo_point_t));
+	if (new_points)
+	    memcpy (new_points, spline->points, old_size * sizeof (cairo_point_t));
+    } else {
+	new_points = realloc (spline->points, new_size * sizeof (cairo_point_t));
+    }
 
     if (new_points == NULL) {
 	return CAIRO_STATUS_NO_MEMORY;